UltraTree Checkbox | Infragistics Forums

@genvej and GoDaddy

I don't know what GoDaddy's implementation looked like, but if someone is looking for code (as I was) I'd like to share the implementation I came up with, based on the Knowledge Base article. Feel free to use as you wish and to improve it. :-)

The checkbox/selection tree view behaves the way I expect it to:

If a node's CheckState changes, then all child nodes (recursively) are updated to the same state (Checked or Unchecked), and also the CheckState of the parent nodes (recursively) are recalculated (to Checked, Unchecked or Indeterminate).

(Of course just put this in a class as GoDaddy suggests.)

---

Imports Infragistics.Win.UltraWinTree

Public Class Form1
    Inherits System.Windows.Forms.Form

    ''' <summary>
    ''' The updatingLock is used because we only want to take
    ''' special actions (HandleTreeCheckedStateChanges(...))
    ''' on Check changes caused by user actions (e.g. clicks)
    ''' and ignore programmatic CheckState changes.
    ''' </summary>
    Private updatingLock As Boolean = False

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call
    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.
    'Do not modify it using the code editor.
    Friend WithEvents baseTree As Infragistics.Win.UltraWinTree.UltraTree
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.baseTree = New Infragistics.Win.UltraWinTree.UltraTree()
        CType(Me.baseTree, System.ComponentModel.ISupportInitialize).BeginInit()
        Me.SuspendLayout()
        '
        'ultraTree1
        '
        Me.baseTree.Dock = System.Windows.Forms.DockStyle.Fill
        Me.baseTree.Location = New System.Drawing.Point(0, 0)
        Me.baseTree.Name = "baseTree"
        Me.baseTree.Size = New System.Drawing.Size(292, 266)
        Me.baseTree.TabIndex = 1
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Controls.Add(Me.baseTree)
        Me.Name = "Form1"
        Me.Text = "Form1"
        CType(Me.baseTree, System.ComponentModel.ISupportInitialize).EndInit()
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        CreateExampleTree()

        '   Add checkboxes to tree
        Me.baseTree.Override.NodeStyle = NodeStyle.CheckBoxTriState
    End Sub

    Private Sub CreateExampleTree()
        Dim i, j, k As Integer
        For i = 1 To 5
            Dim rootNode As UltraTreeNode = Me.baseTree.Nodes.Add("Node " + i.ToString())
            For j = 1 To 5
                Dim childNode As UltraTreeNode
                childNode = rootNode.Nodes.Add(rootNode.Key + " Child " + j.ToString())
                For k = 1 To 5
                    Dim childchildNode As UltraTreeNode
                    childchildNode = childNode.Nodes.Add(childNode.Key + " Child " + k.ToString())
                Next k
            Next j
        Next i
    End Sub

    Private Sub baseTree_BeforeCheck(ByVal sender As Object, ByVal e As Infragistics.Win.UltraWinTree.BeforeCheckEventArgs) Handles baseTree.BeforeCheck
        Dim treeNode As UltraTreeNode = e.TreeNode
        '   Do not allow Indeterminate state for leaves.
        If IsLeafNode(treeNode) Then treeNode.Override.NodeStyle = NodeStyle.CheckBox
    End Sub

    Private Sub baseTree_AfterCheck(ByVal sender As Object, ByVal e As Infragistics.Win.UltraWinTree.NodeEventArgs) Handles baseTree.AfterCheck
        If updatingLock Then Return 'Because the Check change was caused programatically in HandleTreeCheckedStateChanges(...)

        Dim treeNode As UltraTreeNode = e.TreeNode

        updatingLock = True 'Begin handling checked state changes of the tree
        HandleTreeCheckedStateChanges(TreeNode)
        updatingLock = False 'End handling checked state changes of the tree
    End Sub

    ''' <summary>
    ''' When a tree node has been clicked and its CheckState has
    ''' changed we need to update the CheckState of the nodes
    ''' below and above in the tree.
    ''' </summary>
    Private Sub HandleTreeCheckedStateChanges(ByVal treeNode As UltraTreeNode)
        '   Each time a non-leaf node's CheckState changes
        '   1) Make sure it is Checked or Unchecked - we should not be able to make it indeterminate by clicking!
        If treeNode.CheckedState = CheckState.Indeterminate Then treeNode.CheckedState = CheckState.Unchecked ' Since NodeStates: Unchecked => Checked => Indeterminate
        '   2) Set all child nodes to same state.
        SetChildNodesCheckStatesToSameAs(treeNode)

        UpdateParentNodeCheckState(treeNode)
    End Sub

    Private Sub SetChildNodesCheckStatesToSameAs(ByVal treeNode As UltraTreeNode)
        If IsLeafNode(treeNode) Then Return 'End recursion
        For Each childNode As UltraTreeNode In treeNode.Nodes
            childNode.CheckedState = treeNode.CheckedState
            SetChildNodesCheckStatesToSameAs(childNode)
        Next
    End Sub

    ''' <summary>
    ''' Verifies the CheckState of the parent node for the
    ''' specified treeNode, by setting the parent node's
    ''' CheckState property based on whether none, some,
    ''' or all of its child nodes are currently checked.
    ''' </summary>
    ''' <param name="treeNode"></param>
    ''' <remarks>This method only has relevance for non root-level nodes</remarks>
    Private Sub UpdateParentNodeCheckState(ByVal treeNode As UltraTreeNode)
        Dim parentNode As UltraTreeNode = treeNode.Parent
        If parentNode Is Nothing Then Return 'End recursion

        '    Get the nodes collection to which the specified childNode belongs
        Dim nodesCollection As TreeNodesCollection = treeNode.ParentNodesCollection

        '    count of the number of checked nodes
        Dim checkedNodesCount As Integer = 0
        Dim indeterminateCount As Integer = 0
        For Each node As UltraTreeNode In nodesCollection
            If node.CheckedState = CheckState.Checked Then checkedNodesCount += 1
            If node.CheckedState = CheckState.Indeterminate Then indeterminateCount += 1
        Next
        '   Set appropriate CheckState of the parentNode
        If checkedNodesCount = nodesCollection.Count Then
            parentNode.CheckedState = CheckState.Checked
        ElseIf checkedNodesCount = 0 AndAlso indeterminateCount = 0 Then
            parentNode.CheckedState = CheckState.Unchecked
        Else
            parentNode.CheckedState = CheckState.Indeterminate
        End If

        '   Traverse up the tree...
        UpdateParentNodeCheckState(parentNode)
    End Sub

    Private Function IsLeafNode(ByVal treeNode As UltraTreeNode) As Boolean
        Return treeNode.Nodes.Count = 0
    End Function

End Class

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